The `)` line is indented an extra space.

That said: I question the benefits of these specs listing the notifications: it's duplication with the `notifications` method itself. Is there a better way to test that a formatter integrates properly with RSpec?  For example, what about something like this?

* Have a spec that defines some example groups, registers the formatter being tested, and runs the example groups.
* Have it set a `StringIO` as the output stream.
* Set expectations about the resulting output (maybe even as a simple string equality check for the simpler textual formatters).

That kind of approach would be focused on the behavior of the formatter (e.g. what output it produces) rather than the implementation.